I tried using all the markers, but this didn't work. All of them at once, took up too much space and the upper cowl wouldn't fit properly. So I removed all but one marker and it fit quite well. So, cowl on, rap the single marker, pull the cowling and drill out the hole. Move the marker, put the cowl back on, check to make sure the new hole is properly located and rap the next marker... Repeat till all holes have been relocated.